Particulate compositions for removing metal stains, in particular rust stains, from hard-surfaces are known in the art. Indeed, EP-A-1 111 038 describes scouring compositions for removing rust and other metal stains from hard surfaces. Indeed, it has been observed that, especially in countries where poor water piping is still in existence, metal oxidation products, e.g., rust, collects or deposits in the pipe and then flows with the water out of the water outlet pipe onto surfaces located underneath or nearby. The metal deposits collect on the surfaces leaving a sometimes coloured stain. Furthermore, metal-based stains, and rust stains in particular, can appear on damaged iron-containing surfaces (such as stainless steel), in a humid environment such as in the bathroom/shower on metallic containers (shaving gel, personal care products and the like) including on the surfaces in contact therewith as well as in a basements, on garden tools, driveways, garages, etc. Such metal-based stains are difficult to remove with general household hard surface cleaner and require specialist treatment with a rust removing composition.
The currently available compositions suitable for removing metal-based stains, such as rust, from hard surfaces are based on oxalic acid. Indeed, it has been found that oxalic acid provides excellent metal-based stain, in particular rust, removal from hard surfaces.
Another type of stains frequently occurring on hard surfaces found in bathrooms, toilets, garages, driveways, basements, gardens, kitchens, etc., are limescale deposits. Limescale deposits, are formed due to the fact that tap water contains a certain amount of solubilised ions, which upon water evaporation eventually deposit as salts such as calcium carbonate on hard surfaces, which are frequently in contact with water. The visible limescale deposits result in an unaesthetic aspect of the surfaces. The limescale formation and deposition phenomenon is even more acute in places where water is particularly hard. Furthermore, limescale deposits are prone to combination with other types of soils, such as soap scum or grease, and can lead to the formation of limescale-soil mixture deposits (limescale-containing soils). The removal of limescale deposits and limescale-containing soils is herein in general referred to as “limescale removal” or “removing limescale”.
The above described limescale deposits and limescale-containing soils are frequently formed on the above described surfaces that also show a frequent occurrence of metal-based stains such as rust (e.g., bathrooms, toilets, garages, driveways, basements, gardens, kitchens, etc.). Therefore, in addition to showing good metal-based stains (e.g., rust) removal performance, cleaning compositions used for rust cleaning should also show good limescale removal performance.
However, it has been found that even though metal-based stains removal of oxalic acid-containing compositions is excellent, the limescale removal performance of oxalic acid is below expectation. In particular, it has been discovered that oxalic acid-containing compositions are not fully satisfactory from a consumer viewpoint especially regarding their limescale release properties achieved when applied onto the surface to be treated, left to act onto said surface without any further mechanical wiping and/or agitation action, and then removed by rinsing.
Furthermore, it has been determined by consumer research that particulate compositions are less preferred by the user as compared to liquid compositions, as such particulate compositions are less convenient to handle. Indeed, particulate compositions have to be dissolved and diluted in water prior to use, which may confuse the user and represent additional effort. Furthermore, particulate scouring compositions may be abrasive on hard surfaces, in particular delicate surfaces, and are thus less preferred by users.
It is thus an objective of the present invention to provide a liquid hard surface cleaning composition comprising oxalic acid that provides good metal-based stain, in particular rust, removal performance, whilst at the same time providing good limescale removal performance.
It has been found that the above objective can be met by the composition according to the present invention.
It is an advantage of the compositions according to the present invention that they may be used to clean hard surfaces made of a variety of materials like glazed and non-glazed ceramic tiles, enamel, stainless steel, Inox®, Formica®, vinyl, no-wax vinyl, linoleum, melamine, glass, plastics.
A further advantage of the present invention is that the compositions herein are safe to consumers and not damaging to the treated surface, especially delicate surface such as linoleum, glass, plastic or chromed surfaces.